Tamerlan Tsarnaev, the older and apparently more radical of two brothers suspected in the deadly Boston Marathon terror bombings, objected to a sermon at a Cambridge mosque close to Martin Luther King Day this year in which the speaker compared the Prophet Muhammad with King, known for his advocacy of nonviolence, a mosque official said.

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Yusufi Vali, a spokesman for the mosque, said Tsarnaev told the speaker, “You are a kafir [an unbeliever],” and said he was contaminating people’s minds and was a hypocrite.

Vali said, “The congregation then said, ‘You are the hypocrite.’ The congregation shouted him out of the mosque.”

Later, a respected volunteer talked with Tsarnaev and told him he needed to decide whether to stay and not shout out or stop coming to the congregation.

Vali said it was the second time that Tsarnaev had made an outburst during one of the speaker’s sermons.

“There was nothing about it that would suggest that he would kill a person,” said Vali.

Such outbursts are unusual in mosques but not unheard of, said Vali and Imam Suhaib Webb of the Islamic Society of Boston Cultural Center mosque in Roxbury. The two mosques are owned by the same entity but managed separately.

Vali said Tsarnaev “was just expressing his opinion about his belief” and it wasn’t seen as something that would rise to the level of alerting authorities.

Tsarnaev’s earlier outburst had come in November. He had started attending the mosque occasionally about a year ago, Vali said.

The holiday named for the civil rights leader who advocated non-violent protest was about three months before the attacks on Marathon Monday. Striking at 2:50 p.m. in the happy crowds near the race’s finish line, the two blasts killed three people and injured more than 170.

The 26-year-old Tsarnaev, who was killed during a gun battle with police early Friday in Watertown, was allegedly joined in the bombing plot by his brother, Dzokhar, 19, who was captured Friday evening.

Authorities believe the Tsarnaevs also added other victims to their list: MIT Police Officer Sean Collier, who was fatally shot in Cambridge Thursday night, and MBTA Transit Police Officer Richard H. Donohue Jr., who was wounded in the Tsarnaevs’ battle with police in Watertown.